According to market research firm Gartner, Microsoft Windows Vista has failed to stimulate the PC market as many expected and instead had very limited impact on PC demand or replacement sales since the operating system's release.

Worldwide PC sales are expected to total 257.1 million units in 2007, an 11 percent increase from last year’s shipments of 231.5 million units. According to the study, emerging markets are having a much more significant impact on global shipments rather than the launch of Microsoft’s latest OS, and they are expected to contribute 128 million new PC shipments during the next two years, amounting to 25 percent of all PC units expected to be shipped globally during the time period.

“Vendors continue to face a thorny mix of select growth opportunities and serious challenges in mature markets,” Gartner analyst George Shiffler explained. “Continuing strong demand for mobile PCs, especially among consumers, offers vendors tremendous growth opportunities. But generally weak desk-based PC replacement activity and narrowing penetration opportunities, especially among larger businesses, pose some serious challenges.”
Both desktop and laptop computers continue to grow in demand, however thanks to continued price drops, increasing performance, and the spread of wireless access, mobile PC shipments worldwide are forecast to reach 103.2 million units this year, a 27.1% increase from last year, while desktop shipments are predicted an increase of just 2.4 percent from last year, totaling 153.9 million units according to Gartner.